ECG sensing with noise filtering

• US 8,543,195 B1
• Filed: 11/10/2011
• Issued: 09/24/2013
• Est. Priority Date: 11/03/2009
• Status: Active Grant

• Current Assignee: VivaQuant LLC
• Original Assignee: VivaQuant LLC
• Inventors: Brockway, Brian, Brockway, Marina
• Primary Examiner(s): Gedeon, Brian T
• Application Number:
  US13/293,632
• Time in Patent Office: 684 Days
• Field of Search: 600/300, 600/508, 600/509, 600/522, 600/523
• US Class Current: 600/509
• CPC Class Codes: A61B 2560/045 with a separable interface unit, e.g. for communication
• CPC Class Codes: A61B 5/276 Protection against electrode failure
• CPC Class Codes: A61B 5/30 Input circuits therefor
• CPC Class Codes: A61B 5/316 Modalities, i.e. specific diagnostic methods
• CPC Class Codes: A61B 5/335 using integrated circuit memory devices
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal

Abstract

Various embodiments are directed to signal processing. In accordance with example embodiments, methods and apparatuses involve using at least two electrodes that sense an ECG signal. A denoising module is communicatively coupled to the at least two electrodes, and receives the ECG signal sensed by the sensing electrodes. The denoising module includes circuitry that conditions and digitizes the ECG signal, and a computing circuit that processes the digitized ECG signal to denoise the ECG signal. A communications circuit generates a communication including the denoised ECG signal for access by a remote device.

Claims

1. An apparatus for wearing on a body of a live being, the apparatus comprising:

a battery;

at least two electrodes configured and arranged to sense an ECG signal from the live being;

a denoising module powered by the battery, communicatively coupled to the at least two electrodes and configured and arranged to receive the ECG signal sensed by the sensing electrodes, the denoising module including

circuitry configured and arranged to digitize the ECG signal, and

a computing circuit configured and arranged to process said digitized ECG signal to

denoise the digitized ECG signal by increasing a signal-to-noise ratio in the ECG signal by at least 15 dB, and

reconstruct the ECG signal with a quality of signal reconstruction of at least 95%; and

a communications circuit powered by the battery and configured and arranged to generate a communication including the reconstructed ECG signal for access by a device remote from the communications circuit.

2. The apparatus of claim 1, wherein the electrodes are dry electrodes.

3. The apparatus of claim 1, wherein the computing circuit is configured and arranged to process said digitized ECG signal to reduce in-band noise using multi-domain signal processing.

4. The apparatus of claim 3, wherein the computing circuit is configured and arranged to process said digitized ECG signal to reduce in-band noise using principal component analysis.

5. The apparatus of claim 1, wherein the computing circuit is configured and arranged to

denoise the digitized ECG signal by decomposing the digitized ECG signal from a first domain into subcomponents in a second domain,

identify a signal subcomponent in a time segment based upon characteristic frequency content of an ECG in said time segment of a cardiac cycle, and

reconstruct the ECG signal by constructing a denoised ECG signal in the first domain from at least two subcomponents identified as signal subcomponents.

6. The apparatus of claim 1, wherein the computing circuit is configured and arranged to denoise the digitized ECG signal based upon a time-based distribution of subcomponents resulting from decomposition of the signal.

7. The apparatus of claim 1, wherein the communications circuit is integrated with the denoising module in a chip, and the at least two electrodes are directly connected to the chip via a conductive lead, the chip being configured and arranged for wearing by a human and to generate the communication via the communications circuit by generating and transmitting a wireless signal for access by a device remote from the chip.

8. The apparatus of claim 1, wherein the ECG signal has a 3 dB bandwidth of at least 40 Hz.

9. The apparatus of claim 1, wherein the apparatus has a volume of less than 15 cc.

10. The apparatus of claim 1, wherein the computing circuit is configured and arranged to increase the signal-to-noise ratio in the ECG signal by at least 25 dB.

11. The apparatus of claim 1, wherein the ECG signal is a simulated ECG signal, synthesized according to the ANSI EC57 standard for purposes of measuring the signal-to-noise ratio, and the signal-to-noise ratio of the sensed signal is between 0 and 30 dB.

12. An apparatus comprising:

at least two electrodes configured and arranged to sense an ECG signal;

a denoising module communicatively coupled to the at least two electrodes and configured and arranged to receive the ECG signal sensed by the sensing electrodes, the denoising module including

circuitry configured and arranged to condition and digitize the ECG signal, and

a computing circuit configured and arranged to denoise process said digitized ECG signal by

decomposing the digitized ECG signal from a first domain into subcomponents in a second domain,

identifying subcomponents that are associated with noise based upon a spatial distribution of the subcomponents, and

constructing a denoised physiological signal in the first domain from at least two of the subcomponents that have not been identified as being associated with noise; and

a communications circuit configured and arranged to generate a communication including the denoised ECG signal for access by a device remote from the communications circuit.

13. The apparatus of claim 12 wherein identifying subcomponents based upon spatial distribution includes spatially selective-filtering the subcomponents.

14. The apparatus of claim 12, wherein identifying subcomponents based upon spatial distribution includes identifying the subcomponents using principal component analysis.

15. The apparatus of claim 12, wherein the computing circuit is configured and arranged to identify subcomponents that are associated with noise by

identifying signal subcomponents as subcomponents having more signal energy than noise energy, and

identifying noise subcomponents within a time segment of the ECG signal as subcomponents that are not the signal subcomponents.

16. The apparatus of claim 12, wherein the computing circuit is configured and arranged to identify subcomponents that are associated with noise by

identifying at least one time segment of the ECG signal as being associated with noise based upon frequency content of a representative ECG signal, and

identifying subcomponents falling within the at least one time segment as subcomponents that are associated with noise.